JPS58102340A - Optical reproducing device - Google Patents

Abstract

PURPOSE:To start focus control speedily and smoothly by displacing an objective forcibly and then forming a closed loop for the focus control when nearly the best focusing state is obtained. CONSTITUTION:For focus control over an optical video disk player, i.e. control over the interval between an objective and a disk, a saw-tooth wave voltage is applied to a moving coil 8 and the objective 7 comes closer to the disk 1, but when it is not close enough, an error amplifier 12 generates an error output; when the output decreases below a reference voltage E1, the best focusing state is obtained. At this point of time, a switch circuit 17 is turned on to form a closed loop, starting the focus control. Therefore, the starting of the focus control is performed smoothly and a focus control locked state is obtained easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Motogakucho student dress [6] that allows smooth start of focus drawing.

In a Koko type videotask player, when starting focus control, that is, controlling the distance between the objective lens and the disk, if the distance between the objective lens and the disk is outside a certain range, the focus error occurs. It was difficult to start l+lJ +'+lI smoothly.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical writing device which can smoothly and quickly start focusing 1ljj1.

In order to achieve the second object, the present invention provides a 4R2 recording medium 101 rotation drive device for rotating a sheet-like recording medium;
an optical lens for emitting a light beam; an objective lens for converging the beam emitted from the light beam and projecting it onto the recording medium; and an objective lens for displacing the position of the objective lens with respect to the recording medium. a lens driver for driving; a photodetector for configuring reflection or transmission of the optical beam on the recording medium; A focus control signal forming circuit which forms a focus control signal to maintain a constant focus state and supplies it to the lens 1 driving device g;
A switch 1p1 path is provided between the lens drive device and the lens drive device to selectively cut off the transmission of the focus control key signal, and a switch 1p1 path is provided to forcibly move the objective lens relative to the recording medium when starting the focus control j. a lens forced displacement signal supply circuit that directly or directly supplies the lens driving device with a lens strength 1fjll displacement signal to be changed within a certain range; When the focus control signal is being set, Fii detects that the appropriate focus state or a state near it is written based on the output of the focus control signal forming circuit, and sends the switch 1 envelope to the focus control signal transmission '$. ．．
The present invention relates to an optical reproducing device characterized in that it is equipped with a switch control circuit that opens to the open side 1 in the state.

According to the above invention, the objective lens is forcibly displaced to form a closed loop with an optimal focus state, v (focus secondary side at one point in time when is obtained), so focus control can be performed quickly and efficiently. Starting smoothly is the number one skill.

Next, an optical reproducing device θ according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In Fig. 1, (11 is a disk as a sheet-like audio recording medium, and 1 has a '4 signal in the form of an i-line. (2) is Rotation 1 for holding the disc (1) in a freely removable manner and rotating the rotating part M (h'')
1 drive system (6), consisting of a disk motor, turntable, clamper, etc. (3) is a laser beam, and in the case of I/I'qVJ11, it emits an original beam (4) which is used both on the reproduction and focus axis.

The optical system for projecting this beam (4) onto the disk il+ includes a mirror (5), a beam splitter 161, and an objective lens (7). rJ'il and disk (
In step 1), the beam (4) is focused by the objective lens (7) and projected by a distance qτ. Objective lens (7)
is supported in a circular displacement perpendicular to the disk (1) in order to adjust the focal axis of the beam (4) on the disk (lunar surface). !4
This is a descriptive illustration of a voice coil type drive device for displacing the objective lens (7).I3) The objective lens (7) and the moving coil (8) are coupled to the winding frame (44), and the coil (8) is placed within the gap of permanent eigen (45).

In the first driving device of this embodiment, the lens (7) is supported by a gimbal spring in order to improve the control object.
Not yet. ηF means that the current in the coil (ζ) does not become over-focused when it is in a low state, but it is displaced in the vertical direction in response to the focus LllI (I), and becomes the optimal focus axis.

The path of the anti-ET flash L (9) that runs one branch on the disk (1) includes a pair of lenses (7), a beam splitter (0),
Nissho lens H1 and 4-segment photodetector (marks are arranged sequentially).

4 photodiodes I), , D2, 'J3, D4
As shown in FIG. 2, a well-known four-segment photodetector (11) consisting of When you get too close to the disk (1), the focal point fbl is -1
When a spot of electron length is formed and the objective lens (7) is too far from the disk (1), a spot indicated by a chain line [C1] is formed. In order to form the focus-controlled fill signal, the bead 1 and the fourth photodiode D, , D4 are connected together yt3! Connect the second and third photodiodes D2 to the terminals of the width converter 11z
, are connected in common to the positive terminal of the error amplifier (12). The valley photodiodes D, -D are coupled to a reproducing amplifier (15) via coupling capacitors t131 to t141, and a demodulation circuit Bv, tllil is provided at the output stage of the amplifier (I5). Focus City 11 I Kano Igi No Sugi J Le, J Middle 1st Road H Wu Fu 1
There is a focus ? l1ll
1Flt selective transmission switch 1 path 0γ),
A combining circuit (18) and a driving amplifier pupil are sequentially provided,
The moving coil (8) is configured to be driven in response to the error output when the switch iM j171 is on.

In order to use the focusing system 11 side j system to detect the state of abuse of the disk (1) to the drive gamma (2) and to control the start of focus control, the lens is Forced displacement signal supply carp 1! , l'l path (2), and recording medium ejection status, collision detection and switch 1 line 1] control circuit (2b
1st prize will be awarded.

The lens forced displacement signal supply 1p circuit (25) includes a generator 111Ji that generates the control pulse shown in Figure CB), an A N D gate (original), and a side wave generator. It consists of a device tz3+ and a switch circuit (24), and generates the side wave white and pressure shown in FIG. 4U in the JQ1 song that detects the presence or absence of a disc.

The output of this lens displacement input signal supply circuit (25) is sent to a synthesis circuit (18), and is added to or subtracted from the output of switch u7).

Detection of disk attachment/removal status and switch open side] Circuit 121i
+ is the output of the error type width transducer (12) and the first reference phase' pressure 1
A comparator (2't
), a quasi-stable multivibrator +281 which generates a pulse at a certain time in response to the positive output pulse of this comparator γ), and a photodiode D, which is connected to the (29) and this amplifier (29)
a second comparator 6J which receives as input the output of
A delay circuit +:n+ that delays the output of + by a fixed period of one temple,
Monostable multivibrator 1281 output and delay +a
From the example, a N Ofj gate whose input is the output of IQ'r (It) is lJl<.

N(Jl(・Output of gate (32;) and switch circuit (1
7) +(t4 has N(JR gate t,',,i31
is provided, and this N(Jl is also connected to the gate t, 3:(l) to one input terminal of the focus control H, H and detection start operation switch 6.1).

Operation switches 1 and 1i41 are always on, and when operated, they turn off and send out Mr. Lee level (M number Kaoru. ((5
1 is an inverter, (section) is a peak hold circuit,
The inverted output of NOR gate l:j21 is held,
It is sent to the disk presence/absence indicator (3η) and the system controller 81.

The output of the comparator f, 1llll is connected to the output of the comparator f, 1llll. dl, and a branch circuit t, j! to this A'. :11's output and 3's standard Ichikawa E3's TIT source and J&ryji
The third comparator (41, 1) is a circuit that detects the focus servo lock state, and its output controls the forced lens displacement supply circuit (2j), which controls the system controller light. , 4) is informed that the focus servo block shape y(.

Next, referring to FIG. 4, the operation of the 1-1 path in FIG. 1 will be explained. For example, if the start operation switch 134+ is turned off at time 11, either in conjunction with the play switch or the like, a low-level operation output signal is sent out as shown in Figure 4 (AJ).At this time, the #3 comparator (!l1il Since the output of is also at a low level as shown in FIG. 4N, the output of the OR gate 1) becomes a high level,
22i, the 31 pulse from t2 to 13 period r) in Figure 4 (B) becomes a pulse, and the fourth
The pulse shown in Figure (C) is applied, and the side wave cage pressure shown in Figure 4 is 1-1 in the light in synchronization with the trailing edge of this pulse. Also, the switch circuit (2 pieces) is 111 mm, and the NOR gate + 211 is made of wax.
Turn on with cylinder level output? ff1J ml. Therefore, the sea and wave voltages are supplied to the synthesis circuit (181).
, J (a voltage corresponding to the side branch voltage is supplied to the moving coil (8) regardless of the revetment output, and the lens (7) is gradually displaced. Note that the low level output of the operation switch (34) is NOR Since it is the input of the gate (, (:(l), the input of the gate 13jl is ``The output is kept at a low level as shown in No. 4-0, and the switch ``U'' path 1471 is kept off.

In this actual case 1, the lens (7) and the moving coil (8) are not supported by the gimbal spring, and the objective lens (7) and the disk 11) are Since the spacing is outside the +# range, at the beginning of the saw plate voltage, the beam (4) is connected to the disk (1).
The reflected light (9) is also in a blurred state, and most of the reflected light (9) enters the photodetector 111) and does not go up. Therefore, the output and focus of the increaser 1M (29j) for detecting the presence or absence of incident light on the photodetector (11) and the erroneous run to form a signal on the photodetector (11) are
The output of positive device U2+ is substantially low. Thereafter, the objective lens (10) gradually approaches the disk (1) due to the saw plate voltage, and when the spot of the beam (4) on the disk (11) becomes well converged, the incident light of the photodetector (11) increases. The convergence state of the old light also improves, and the output from the amplifier (甜) becomes unreliable. Also, an error output is obtained from the error amplifier (la) indicating that it is too far from the lens (7) or the disk (1). It will be done.

As the convergence state of the light incident on the optical horizontal output device (former) becomes better, the output of the error intensifier (12) increases and reaches a peak. In this example, the peak in the positive direction shown in the 41st lens (6) indicates that the lens (7) is ft+ft from the disk (11).
It shows that it is too much. Even when the output of the error amplifier (121) reaches its peak, the lens (7) is further connected to the disk (1).
Since the saw plate voltage is applied so as to approach the disk (11), the lens ('l) gradually approaches the disk (11) and becomes in optimal focus. That is, the error as shown in Fig. 41 The output decreases from the positive peak toward the bottom and becomes below the first reference pressure El at time 16. In this example,
Focus?tjll ml is started in synchronization with the 10th point in time when the error output becomes I''i1.
By comparing J, 1 with the reference Ichikawa E, the comparison output pulse shown in Fig. 4 (Q) is obtained.
-he time t6, the lens (7) is at the saw plate voltage and the disc (
1), which indicates that the optimum focus has been reached. Therefore, in order to turn on the switch circuit +171 of the focus sub-side 1 signal transmission line at the 16th point, the monostable multivibrator 1281 is triggered at the 16th point to generate the pulse shown in FIG. This monostable multivibrator (z8) has a function that prevents the switch circuit (17) from responding even if the output of the comparator (27) vibrates due to noise etc., and also locks the focus side tilt j by the operation of the 11th P1. If you fail to obtain the lock state, you will be responsible for the second focus sub-side [to make the operation to obtain the lock state properly]. Therefore, a monostable multivibrator (28
)'s output pulse 11"η is the side wave ratio: pressure generation period'
It is set smaller than 1.2.

Comparator on side 2 (J 4 t in 3111
As shown in A (F), the 1S signal corresponding to the light input of the photodetector (111) and the reference voltage E2 are compared, and at the 16th point in time when the light output signal with the reference pressure E2 or higher exceeding the noise level is input. The specific soft output changes to the quotient level as shown in FIG. 4(I).

I'm moving to this level! 8fru t5 l++, 1 point is before the apical focus point 16, so year 4 figure (1
) is shifted to the 18th point shown in FIG. 4(J), which is after the 16th point in time, by the delay 1].

If the presence or absence of disk (11) is to be investigated, this delay time 1 (3I) is unearned, and Fig. 4 (I
) may be used as extrusion No. 1d with a disc. However, in this embodiment, the output of the monostable multivibrator (public) shown in FIG.
After turning on l'l'l, a second comparator (, (
Since the output of IJI is delayed, there is a hassle of delaying the 16th point to the 18th point.

The output of the single constant Martino (the output of the ibrator tZ31 and the delay circuit 61 shown in FIG. 4 (J)) in FIG. 4 (■) is a NOR.
Since it becomes the input of gate 13ij, when the input power of Isuha or 10,000 is at a high level, the output of IN Oi + gate (acknowledgement) is at a low level. (N shown in K (Jl 7th game) tl (2+ output and operation switch f l:34+ low level 1g M are input to the next stage lNOR gate U3+, as shown in Figure 4 A level output is still generated between the low level M, and at the 16th point, the switch is turned on (15 each + i7).
1 loss (j. Focus city lj what 1 silk 66 side) If it is possible to do so, even if the output of the multi-vibrator (28) becomes low level at the time of 0, the 4th Since the signal in figure (J) is at the cylinder level, the switch circuit tl
The on-open side 1 of n is continued.

]The output of the gate NUi is also supplied to the peak, i.e., level hold 1111(,'+6J) via the inverter 135+ to detect the presence or absence of the disk (1). If No. 1 becomes easy level in reversal 1,
This medical signal will not be sent to the display -1 + position (, 3η and the system controller). In addition, the focus lock operation on the d 1 jrql will lock the 4Hr center. If the focus lock is established, the hold circuit +:3 [i) is not necessary, or if the focus lock is not established reliably, it is necessary.νIJ, the first focus lock operation is However, the Focus City 11 side did not become 1 or iJ Noh, P) Hi#, (Izaka'
...When performing a focus lock operation with the help of pressure, the output of the inverter (35) returns to a low level. Therefore, if there is no hold circuit (36), the 1
@ Even though the output signal is turned off and the disc (1) is on, I am thinking of not having it. For this purpose, if a hold circuit (section) is provided, the initial detection of the presence of a disk is held as is, and the disk presence/absence detection signal is not interrupted.

This outfit? In the warehouse, accurately measure the focus opening side 1 sash FH.
In order to obtain T, the output of the second comparator (301) is integrated by the integrator circuit (301) as shown in FIG. If the focus ?1T11ff1l fails to lock, the output of the photodetector (11) will be It virtually disappears as shown by the dotted line.

For this reason, the output of the comparator 3 (+1) of the main 2 is also
At T3 in Figure (I), the level remains for a short period of time before switching to a low level. In such a case, the output of the integral 1 and 1 will increase as shown by the dotted line in Figure 4 D, and g
3, the human power of comparator (10) does not fall to the standard 'Ichikawa E'. Therefore, when the focus lock state is set to the side, the operation for locking the focus open side (m210.1) becomes the closing point.

As shown in FIG. 4, when the focus city II Tsukuda 1 is locked by the operation of the second point II, the output of the comparator 140) of the criminal 3 becomes a high level at the '7M' point, and the system controller locks the focus. i; 31 (notifies 1, and = +7 parator (40) ^ level output is I
N OR gate (21) is input, and the output of this 1\01 (, game) 1zli becomes a low level, the switch circuit i circuit 1241 of the Miyanami output line is turned off, and the supply for the saw blade is turned off at the 17th point. Hal stopped.

Therefore, after t, the moving coil (8) is not driven with a width of 5 voltage corresponding to the output of the error amplifier (12), so that the distance between the lens (7) and the disk (11) is kept constant. It becomes a control part.

If the distance between the disk (1) and the lens (7) is smoothly adjusted to the desired distance at the start of focus control, the lens (7)
) is significantly shifted from the optimum focus state, the focus control becomes zero TNU, the optical input of the photodetector 51111 becomes an extremely low level, and the output of the photodetector amplifier (29) becomes substantially low. In this case, as mentioned in 1a-f, since the high level output period of comparator 2 (, 3(5) is extremely short, the third comparator (40) or I
When the q7 orcus lock detection signal is turned on, the heat wave voltage is continuously supplied as shown by the dotted line in the fourth diagram, and the heat wave voltage of the next cycle causes the objective lens (7) to move toward the disk (1). ) is displaced from a far position to a position close to 1#, and reaches the optimum focus position, at which closed-loop focus control is restarted.

As is clear from the above, in this blind case, the error amplification device (
A comparator (2 forces) is connected to the output line of 12) to detect the point near the optimum focus, and at this point the switch circuit (I7) is turned on to form a closed loop and start focus Ill iAI. Entering focus control becomes smooth, and the focus control @j lock state can be easily obtained.

In addition, a stable multi-vibrator 128) is provided to maintain the closed loop focus 4171411 state for a certain period of time regardless of the output of the comparator 1, so even if the output of the comparator 0 vibrates, the focus control fil can be kept stable. It becomes possible.

In addition, the first and second comparators t271 (30j
The output of N01(, gate L'(2) is input, and this output controls the switch circuit side, so focus control is performed.

gH can be easily achieved.

In addition, an integrator circuit 139) and a third comparator (41Jl
Since the focus lock state is detected by this, if the focus lock state is not achieved, it becomes possible to start focus control by supplying the heat wave voltage again.

Furthermore, since the focus control system is used to detect the presence or absence of the disks t and 11, it is possible to easily detect the presence or absence of the disks.

Furthermore, by detecting the presence or absence of a disc, it becomes possible to clearly determine the presence or absence of a disc from the outside, and an easy-to-handle device can be provided.

In addition, if a signal indicating the presence or absence of the disk (1) is input to the system controller, it will be possible to easily determine whether the information can be read or not, and in the case of search playback, playback will not be possible. This eliminates the problem of regarding the play period as the search period.

Although the embodiments of the present invention have been described above, the present invention is not limited to kneading and can be further modified. For example, as shown in FIG. 5, a switch circuit (46) is provided at the front stage of the drive amplifier (19), and the drive amplifier O9 is connected to the saw blade generator 1231K only when starting the disc detection and focus side 1. , the error 'M width amplifier (la is the drive amplifier u9) shown in FIG. 1 may be connected at the time of the optimum focus position.

Alternatively, the light beam (4) is projected obliquely onto the disk (1) as shown in No. 61A without using a four-part photodetector,
It is also applicable to a method in which the reflected light (9) is detected by a two-segment photodetector (former) to perform focus detection.

In addition, as shown in FIG. 7, in order to drive the objective lens (7), first and second moving coils (8a) (
8b) is provided, and a saw plate voltage is applied to one coil (8a) at the start of disk presence/absence detection and focus control j, and a focus control signal is applied to the other coil (8b) after focus control is locked. It's okay.

In addition, the synthesis circuit (18) in FIG. 1 is configured with an operational amplifier as shown in FIG.
The output of 2) may be inputted, and the sawing pressure may be inputted to the resistor R1 and the resistor R1.

Also, the lock state of focus 1 rA+ is integrated 1 time.
Instead of detecting with the third comparator C3tl+, the monostable multivibrator is triggered by the output of the second comparator C3tl+, and the output pulse of this output pulse is
At the edge, it is detected that there is still an output from the second comparator 30+, and a focus lock shape or crosspiece may be used.

In addition, if you want to obtain only the detection key code for disc presence or absence,
The output of the second converter signal 1.30i may be held and this may be used as a signal indicating that a disc is present. The switch (34) may also be responsive to closing of the player's lid. Further, the light beam (4) may be either visible light or non-visible light. Furthermore, although the feeding mechanism for the light beam (4) in the disk radial direction is not shown in FIG.
) and the light beam (4) is the relative feed between the beam (4)
) This is achieved by moving the disk (1) in the radial direction or by moving the disk (1).

However, it is not limited to directly displacing only the objective lens (7), but by displacing the Niu head including the objective lens (7) with respect to the disk +1.1, the relationship between the objective lens (71 and the disk il+) It is also applicable when adjusting or controlling the tf5 interval. It is also applicable when the objective lens (7) is supported by a gimbal spring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a disk reloading gear according to an embodiment of the present invention, FIG. 2 is a plane diagram illustrating the relationship between a photodetector and a spot, and FIG. 3 is a diagram showing a lens driving device. Fig. 4 is a waveform diagram showing the state of points A to 0 in Fig. 1, Fig. 5 is a block diagram showing a modified example of the saw plate voltage supply section, and Fig. FIG. 7 is a block diagram showing a modification of the lens driving device.
FIG. 8 is a block diagram showing a modification of the synthesis circuit. In addition, in the symbols used in the drawings, the crests are disks, (2) is a disk rotation drive device, (3) is a laser beam, and (4) is a light beam. Agent Noriji Nashino

Claims (2)

[Claims] (1) a recording medium rotation drive device for rotating a sheet-like recording medium; a light source that emits a light beam; and an objective lens that converges the light beam emitted from the light beam and projects it onto the recording medium; a lens driving device that drives the objective lens so that the position of the objective lens with respect to the recording medium is displaced; a photodetector that detects reflected or transmitted light of the light beam on the recording medium; a focus sub-side J signal forming circuit which rejects a focus open side L signal for keeping the focus state of the front 61 light beam on the recording medium constant based on the output of the detector and supplies it to the lens driving device; , a switch circuit for selectively blocking the transmission of the front g+2 focus side j signal, which is provided between the focus control pair forming circuit and the lens driving device, and the focus 71711 side]. a lens forced displacement signal supply circuit that directly or indirectly supplies a lens forced displacement signal for forcibly changing the position of the front ruby objective lens with respect to the recording medium within a certain range to the front lens driving device; In addition to changing the position of the front lens using the lens forced displacement signal, it is possible to determine whether the optimal focus state or a state near it is reached based on the output of the focus sensor 1j formation circuit. An optical reproducing device comprising: a switch control circuit that performs focus control on the switch circuit when the punch is removed. (2) The optical reproducing device according to claim 1, wherein the forced displacement signal supply circuit is a side wave supply circuit that supplies a sawtooth voltage. 131 siJ The light distribution detector is a split-type photodetector whose output ratio changes according to changes in the focus state, and the focus control signal forming circuit is an error amplifier connected to the split-type photodetector. Yes 1, the switch control circuit includes a comparator that compares the error output of the error amplifier tTJ with a standard market pressure near zero, and d1. The reference voltage is substantially similar to the trailing edge of the soft output pulse that the error output is joined by cutting the switch circuit at 1g.
2. The optical reproducing apparatus according to claim 1, further comprising a switch-based m+ signal forming circuit for forming a 1 or 1 signal to control the signal transmission state.